A railway vehicle comprises an underframe, a body supported by the underframe and at least two bogies coupled to the underside of the underframe.
A solebar (sometimes referred to as a sole bar, sole-bar or side sill) is a longitudinal structural member of the underframe. Conventional solebars have a box or channel-shaped cross-sectional profile.
As shown in FIG. 1, a conventional railway vehicle underframe is an oblong frame comprising a first solebar (1a), a second solebar (1b), a first headstock (2a) and a second headstock (2b). The first solebar (1a) and the second solebar (1b) extend lengthwise forming the longitudinal side members of the underframe. The first headstock (2a) and the second headstock (2b) extend crosswise between the ends of the solebars forming horizontal end members. In the underframe depicted in FIG. 1, the solebars have a channel shaped cross-sectional profile. The sidewalls of the railway vehicle body are mounted on the solebars. Hence, the design of the solebar influences the size, shape and volumetric capacity of the railway vehicle body. Buffers (3) and drawgear are mounted on the headstocks. Bogies are typically coupled to the underside of the underframe using bolster members (4). Further cross-members (5) may extend between the solebars and/or the headstocks to improve the structural integrity of the underframe.
So as to ensure safe passage of the railway vehicle along a railway track, across bridges, through tunnels, via other railway structures and past other railway vehicles etc. the design of a railway vehicle must comply with the loading gauge. The loading gauge defines the maximum permissible railway vehicle dimensions, certain suspension displacements and certain curve overthrow limitations for the railway route. A loading gauge has an upper sector and a lower sector. The lower sector loading gauge is the area up to and including a predetermined height above the rails. The height may be determined by the height of the railway platform. For example, the standard lower sector for freight vehicle gauges in the UK is the area up to and including 1000 mm above the plane of the rails. The profile of the upper sector loading gauge is typically stepped or offset from the profile of lower sector loading gauge. As a result, the upper sector loading gauge has an outdented profile relative to the lower sector loading gauge.
To help ensure the railway vehicle has loading gauge clearance, the solebars of a railway vehicle must be configured to fit within the loading gauge.
Whilst conventional solebar designs are able to achieve a sufficient loading gauge clearance, it is understood that, due to the configuration and position of the conventional solebars, the mounting and subsequent arrangement of the body sidewalls on the solebars is restricted and so the shape, size and volumetric capacity of the railway vehicle body is constrained (limited, compromised). For example, FIG. 2 depicts a partial end view of a conventional railway vehicle with the underframe depicted in FIG. 1. It can be seen in FIG. 2 how the channel shaped solebars (only 1b shown) are configured as longitudinal side members of the underframe such that they are arranged within the lower sector loading gauge (LOWER SECTOR) of the railway vehicle. Hence, the underframe of the conventional railway vehicle has loading gauge clearance in the lower sector. Due to the channel shaped cross-sectional profile of the solebars, each sidewall (only 6b shown) of the conventional railway vehicle body is mounted on the solebars such that a mounting portion is coupled to the inner surface (IN1) of the respective solebar, an inclined portion inclines in an upwardly direction within the upper sector loading gauge (UPPER SECTOR) from the inner top edge of the solebar until it is close to the upper sector loading gauge boundary and then an upright portion extends in a generally upwards direction. The interior volume of the underframe is determined by the distance between the inner surfaces of the solebars which, as shown in FIG. 2, is confined by the cross-sectional width of the solebars. The shape of the railway vehicle body is influenced by the mounting arrangement of the sidewalls and cross-sectional width of the solebar. The size and subsequently the volumetric capacity of the railway vehicle body are determined by the distance between the opposing sidewalls of the railway vehicle body, which in turn is governed by the mounting arrangement of the sidewalls and the cross-sectional width of the solebar. It can be seen in FIG. 2, that due to the mounting arrangement of the sidewalls and the cross-sectional width of the solebars, the inclined portions of the sidewalls do not comply closely (correspond, match) with the profile of the upper sector loading gauge as they extend from the solebar. Moreover, the gap space between the inclined sidewalls and the upper sector loading gauge is substantially greater than is necessary to achieve loading gauge clearance. Hence, although loading gauge clearance of the railway vehicle body is achieved, the shape, size and volumetric capacity of the conventional railway vehicle body are restricted.